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Are rabbits really to blame for last summer's outbreak of
tularemia and for what could be a repeat performance this year?

Sam Telford, a parasitologist from Harvard University and
the newest member of a team sent here to investigate why such a
rare disease has taken hold on the Vineyard, doesn't think so.
What's more, Mr. Telford is just as skeptical about the
prevailing theory that most victims breathed in air particles
contaminated with the tularemia bacteria.

His own hypothesis? An increased population of rats, not
rabbits, could be a big factor. "The dogma out there is that
it's rabbits," Mr. Telford said Friday in a telephone interview.
"But [at Harvard] we're focusing on rats as the so-called
inter-epidemic reservoir. Rabbits are poor reservoirs because
they die from tularemia. If rabbits are the reservoir, then how
does tularemia keep going from year to year?"

Bucking another assumption about the disease which killed a
Chilmark man last summer and infected 14 others, Mr. Telford
argued that it's possible to get pneumonic tularemia from a tick
bite and not from inhaling bacteria-laden air particles.

"That reflects a controversy in the tularemia medical
literature itself," he said. "Not every instance of primary
pneumonic tularemia is a result of exposure by aerosol. That's
what I have an issue with. You have to have an alternative
hypothesis. There may be a combination of factors. Some may have
gotten it by tick bites and some may be inhaling it."

According to Mr. Telford, it is entirely possible to
contract the pneumonic form of the disease from a dog tick bite.
And, he added, since not all tick bites result in swollen
glands, the absence of that one symptom in a person with
pneumonia should not be used to rule out a tick bite.

Mr. Telford, who is a lecturer at the Harvard School of
Public Health, has been studying Lyme disease on the Vineyard
for the last seven years and on Nantucket for most of the last
15 years. And while his theories run right against the grain of
what state and federal public health officials have assumed for
the last year, he doesn't see himself butting heads with the
team he has just joined - the Centers for Disease Control and
Prevention (CDC).

"We disagree over the source [of the tularemia outbreak],"
he said. "But we've forged an alliance with the CDC, and
everyone will benefit."

When the CDC heard that Mr. Telford's team from Harvard was
adding tularemia to its list of tick-borne illnesses, he was
invited to join the latest investigation, prompted by last
week's confirmation of the first case of pneumonic tularemia so
far this year. Five other cases are still being evaluated.

Today, landscapers across the Island have been called to
stop by the state forest headquarters to help in the study. They
will give blood samples and receive free, confidential testing
for tularemia. They will also answer a short questionnaire.

Landscapers are considered to be at the highest risk for
contracting tularemia. Last year's CDC investigation found that
11 of the 15 people infected had been mowing a lawn or cutting
brush within two weeks of experiencing the first flu-like
symptoms of the disease. That fact led scientists from both the
state and the CDC to speculate that victims had inhaled dust or
grass clippings that contained the bacteria, present either in
rodent feces, urine or the rodent carcass itself.

Public health officials began warning people to wear dust
maks when they engaged in any outdoor work that would kick up
such dirt and dust.

But Mr. Telford pointed out that scientific knowledge about
inhaling tularemia bacteria is based on one single study done in
the 1950s. "People have been making a major assumption about
inhalation, but much of that understanding comes from one
experiment that the Army did with human volunteers," he said.

The Army experiment exposed the volunteers to 25 different
organisms through a gas mask, Mr. Telford said. "That's very
different from being on a lawn with a breeze blowing in your
face," he added. "This study has just never been critically
questioned."

But tularemia is a virulent bacterium, so potent that it is
considered one of the top agents in biological warfare or
terrorism. Last year, the CDC dispatched experts in
bio-terrorism to the Island to investigate the outbreak and to
road-test new equipment designed to deal with biological
attacks.

And Mr. Telford said that while no one believes the Island
is the object of a bio-terrorist assault, the CDC can't help but
understand the implications of what has happened here and may be
happening again in light of bio-terrorist threats.

"This is a very rare opportunity to have something in our
own backyard like this and with all the emphasis on
bio-terrorism," he said. "If we can't understand how people are
getting it in a relatively small community, how on earth are we
ever going to respond to a bio-terrorist attack of tularemia?"

The Vineyard is the only place in the country ever to
experience an outbreak of pneumonic tularemia. And last summer's
outbreak marked the second time it's happened. Back in 1978,
another outbreak also infected 15 people.

"In the ecology of vector-borne disease, we know that the
bacteria is always around at a low level," said Mr. Telford.
"But for some reason, the transmission has increased over the
last couple years."

The problem is that scientists know very little about how
the bacteria exist in that "constant, low-level state." All
kinds of theories have cropped up to explain the Island's two
outbreaks. One has blamed wet weather in both those years.
Another has tried to point the finger at rabbits, the most
prevalent carriers for the disease commonly known as rabbit
fever.

But Mr. Telford has now focused on rats. On anecdotal
evidence alone, their numbers have risen. The county last week
reinstated the rodent control program, hiring a new officer and
charging him with mounting a campaign not only to cut down the
numbers but also to educate Islanders about keeping rats and
rodents at bay. Officials have blamed the closing of Island
landfills for the increased rat sightings.

And Mr. Telford said the rats could be spreading the
tularemia bacteria, playing host to dog ticks before they bite
humans and infect them. In last year's CDC study, the only
animals to test positive for tularemia were a Chilmark skunk and
a Katama rat. Still, the CDC had trapped a total of 11 Norway
rats.

Whatever the source for the tularemia, Mr. Telford is
enthusiastic about getting to the bottom of this mystery. That
rare opportunity he spoke of is also a scientific challenge. But
it carries economic implications, too. "There are rumors that
tourist numbers are down because they hear there's something you
can breathe in that can kill you," he said. "One has to be
careful when making recommendations. The Island depends on the
tourist economy."

The fact is, Mr. Telford said, that tularemia is a very
treatable disease if caught early. And like all tick-borne
illnesses, he added, in most cases, it can be prevented by
dilgent tick checks.